Age hardenable nickel alloys



Patented July 18, 1950- AGE HARDENABLE NICKEI) ALLOYS Clarence George Bieber and Mortimer Pierce- Buck, fluntington w. Va., assignors to The International Nickel Company, Inca, New York, N. Y.', a corporationof Delaware NowDrawing." Original application January 13,- 1941, Serial N0.-3'74,208. Divided and'thisalp plioation -June-7 ,'.l 94l, SerialNo. 3971180 2 Claims; (Cl. 75-170) 'Ihepresentfinvention relates to nickel alloys, and, more particularly; to age'hardenable nickelcopperalloysi It-is' among the" objects of our invention'to produce nickel alloys capable of' being hardened byheatti'eatinent to any-selectedhardness over a broad hardness range; to provide nickel alloys having maximum hardness in the aged condition commensurate with satisfactory forgeability; and goodqmachihihg :propei'ties;-'and to produce nickel alloys having a-broadi range of hot-malleability combined'with high mechanical propertiesinthe age hardened condition;

Other objects and advantages of the present invention will become apparent from the following description of the pr'esenti-invention;

Generally speaking, the present inventionis based upon the surprising: discovery madeby us that nickelrbase alloyscontaining.v copper and having among other desirable properties an ad.- vantageous combinationofihot malleability, good-- machiningproperties good response to heat treatment and high hardness in theheattreatedcondition can be produced byv incorporating: aluminum=with both titanium and silicon inrthe alloy. in critical amounts depending upon the nickel content, as hereinafter described. Response toheat treatment can be obtained in copper-containingnickel base alloys bydhcorporating only one of "the elements aluminum, titanium or silicon in thealloy but the amount .of hardening. element necessary to produce maximum response to heat treatment is relatively large and this is accompanied by; working. dimculties We havev made the surprising discovery that by using aluminum in combination with silicon and; titaniumgthe response to heatTtreati-nent'with asmaller total "amount 10f hardening element is as satisfactory or even better than in alloys contair'iin'g-,-only,one of these hardening elements in eifective amounts, and'the new alloys are characterizedfby greatly, improved hot malleability. ascompared-with alloys. of otherwise substantially the. same composition containing. only. one of the hardening elements. 7

The'nickel content offthe alloys embodyingthe present invention in allcases ,will be at .least 45%. by. weightof the alloy and 'usually will'be 50 or substantially more than. 50%. Copper will be present'in amountsu-p to 45% of thealloy.

The relative. amount's ofialuminum, silicon and titanium may,vary,.over arange of several percent! provided the ratio. of nickel tothehardenercontent is maintained within the limits. defined 2. ments of" the group titanium" and silicon r'nust each be I present in the alloy in amounts greater than 0.25 The third hardening" elementmaybe p're'sen't' in I amounts-more or less than 0". 25 the" essential featilt'e of this invention -b'ei-ng that titanium range the optimum range of hot malleability, hardenability and high hardness in the heat treatedcondition is obtained-when the ratioof nickel to-thesum. of' the alum'inum;..2.3' times the titanium and the siliconi's approximat'ely 15', preferablywithin the range. of .13"to. 17,.

and always within the range ofllito zbl Since the'ratio isa quotient, it"is immaterial what unit of Weight is used to express the-content offnickel,

aluminum, titaniumand" silicon. Thus,.for ex-v ample; thea'm'ounts' ofithese ingredients in. anygiven alloy may be expr'essed in parts by weight;

percentage by, weight, .etc., without changing .the ratio;

The'mechanical properties-of the nickel-cop per alloys having combinations ofthe hardeningeleme'nts contemplatedby the present invention are, to a considerable extent, improved. by. the

presence of carbon,v provided the carbon is present in? amounts less than about 0.5% The .beneficial'eifect of carbon in the. alloys containing aluminum and titanium is'isurprisingimviewof the known detrimental efiectofcarbon on nickel alloyscontaining jtitanium as substantially. the" only. Hardening element. v

Thev adverse effectof 1' carbon on .theharderlability of alloys containing. titahium as substantially the only hardeningjelement isb'elieved-to 1 bedue to the formationo'f an' inerti titanium car.- bide which decreases. the" hardening,eiiici'ency, of the titanium or destroys its hardening. ability.

The fact that carbon has a beneficialeffcton alloysof the present invention isQbelieved-to indicate that the inert; titanium. carbide. does not form ina substantial amount when aluminum.. is present'with titanium, providedvcarbondslessthanabolut' 0.5% andprefrab'ly. does not-exceed about'0J35-%; For general-applications itisprer ferreclv to have. carbon present in-amount s bev tween about 0.15I.to.- 0.2%; although higher.

herein, Aluminumandat leastronelofl'thefielefilhamounts may. be present; If carbon. exceeds about 0.2%, precipitation of graphitic carbon may Element Per cent Aluminum 25- 5 Titanium 25 2 Silinnn Q 25- 2 Carbon- 0. 03- 0.5 Copper.. -45 Nir-kpl Balance Manganese and iron may be present in the alloy in amounts not exceeding about 2% and 10% respectively. In commercial alloys of the present invention these elements usually are present in small amounts. Ordinarily, manganese will not exceed about 0.5% and may be as low as 0.25%

metal from the group silicon and titanium manufactured in accordance with the present invention are less susceptible to loss of strength and/or ductility after exposure for long periods of time at temperatures of approximately 500 F. to approximately 1100 F. than comparable alloys hardened by one of the elements alone. The new alloys retain their high properties at elevated temperatures, for instance, at steam temperatures of about 1000 F.

The titanium-bearing material possesses improved hot ductility and strength without detrimental effect upon other mechanical properties or the method of heat treatment necessary to procure the mechanical properties. The alloys of the present invention posses improved hot ductility within the hot working range of about 1400 F. to about 23-00 F. The difierences in hot ductilities of the titanium-free and the titaniumbearing alloys contemplated by the present invention are very pronounced. For example, a titanium-bearing alloy had a hot malleable range of about 800 F. or more, whereas a titanium-free alloy had a hot malleable range of only about 400 F. Data from typical melts are given in Table I.

T. S. =tensile strength in thousand pounds per square inch.

or even 0.05%. Iron ordinarily will be less than about 1% and may be present in amounts as small asy0.2% or even 0.05%. ganese apparently afiect the base alloy only and do not afiect' the response of the alloy to heat treatment.

The alloys of the present invention can be heat treated in accordance with the technique developed by Mudge and described in U. S. Patents, Nos. 1,755,554 through 1,755,557, or in accordance with the process of our prior application, Serial No. 253,350, now Patent No. 2,234,955 dated March 18, 1941. Generally speaking, the articles are heat treated subsequent to mechanical working, machini ng and forming operations, but under certain conditions the articles may be exampla fine spring' wires may be cold drawn after the hardening heat treatment since this procedure develops the highest mechanical propto eliminate any discoloration and warping which may occur during heat treatment. Heat treated material may be subjected to subsequent machining, stamping, orother fabricating operations Whenever necessary.

Hot rolled material having the composition contemplated by the present invention will heat treat'to Brinell hardnesses in excess of about 265, and about 300 Brinell represents. an average value. Cold drawn or cold worked material in 1 small sections, e. g., up to about one inch in sectional'thickness, generally heat treats to Brinell 1 hardness values of about 325 or more.

Nickel-copper alloys containing aluminum'and Iron and man- 3 heat treated before the final operations. For i 1 erties. attainable in the material. It also pro- =yie1d point in thousand pounds per square inch.

It will be seen from the foregoing description and the specific examples that we have provided nickel alloys combining optimum response to heat treatment with hot malleability. These alloys may be used for various articles of manufacture including rollers and bearin balls, bearing and races therefor, roller chains, drop forgings and tie rods for airplane construction, valve seats and other valve parts, pump rods andthe like, pump rod sleeves, pump pistons for high pressures and temperatures, plungers, turbine blades, turbine diaphragm blading, lock washers, screws and nuts, tools, cutting blades and the like, pins and needles, spring and other resilient elements, airplane instrument parts, nozzles for burners, rods, sheets, strip, wire, bars, rolled shapes, etc.

The present application is a division of our prior copending application Serial No. 374,208

filed January 13, 1941, and which itself is a continuation in part of our prior application, Serial No. 253,350, filed January 28, 1939, and which issued on March 18, 1941, as Patent No. 2,234,955-

The present invention is not to be confused with our said prior Patent No. 2,234,955. It is to be observed that the present invention involves the discovery that a critical ratio of the nickel content to the content of aluminum, titanium and silicon must be maintained within the critical limits disclosed and claimed herein in conjunction with the special composition set forth in the content being at least 50% of the alloy, the ratio I of the content of the nickel to the sum of the aluminum, the silicon and 2.3 times the titanium being between 13 and 17, and at least a portion of the carbon in the alloy being in the form of l0 graphite.

2. A free machining, age hardenable alloy containing 10% to 45% copper, over 0.25% and up to 5% aluminum, over 0.25% and less than 1% titanium, 0.25% to 5% silicon, 0.2% to 0.35% carbon, 0.05% to 2% manganese, 0.05% to 10% iron, and the balance substantially all nickel, the nickel content being at least 45% of the alloy, the ratio of the content of the nickel to the sum of the aluminum, the silicon and 2.3 times the titanium being between 11 and 20, and at least a portion of the carbon in the alloy being in the form of graphite.

CLARENCE GEORGE BIEBER.

MORTIMER PIERCE BUCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,572,744 Mercia Feb. 9, 1926 1,610,262 Cooper Dec. 14, 1926 2,048,166 Filling July 21, 1936 

2. A FREE MACHINING, AGE HARDENABLE ALLOY CONTAINING 10% TO 45% COPPER, OVER 0.25% AND UP TO 5% ALUMINUM, OVER 0.25% AND LESS THAN 1% TITANIUM, 0.25% TO 5% SILICON, 0.2% TO 0.35% CARBON, 0.05% TO 2% MANGANESE, 0.05% TO 10% IRON, AND THE BALANCE SUBSTANTIALLY ALL NICKEL, THE NICKEL CONTENT BEING AT LEAST 45% OF THE ALLOY, THE RATIO OF THE CONTENT OF THE NICKEL TO THE SUM OF THE ALUMINUM, THE SILICON AND 2.3 TIMES THE TITANIUM BEING BETWEEN 11 AND 20, AND AT LEAST A PORTION OF THE CARBON IN THE ALLOY BEING IN THE FORM OF GRAPHITE. 